Diversity analysis of guava (Psidium guajava) germplasm collection

Guava (Psidium guajava L.) is one of the commercially important cultivated fruit crops in India. Guava ranks fifthin production share of fruit crops in the country. During 2014-15, India produced 36.68 lakh tonnes of guava from anarea of 2.68 lakh ha with 13.7 t/ha productivity. In the present investigation, a total 33 genotypes including 6 speciesof Psidium and 28 genotypes of Psidium guajava were characterized using 39 SSR markers. All accessions are beingcultivated at IARI research farm, Pusa campus, New Delhi. Samples were collected from research farm to determinethe overall diversity and to assess the similarity among genotypes using molecular markers. Out of 39 primers 26were reproducible. A total of 64 alleles were produced by 26 primers and number of alleles per locus variedfrom 1 (mPgCIR01, mPgCIR18 and mPgCIR19) to 5 (mPgCIR256) with mean value of 2.34. Gene diversity rangedfrom 0.0377 to 0.6681 with a mean value of 0.2766. Highest gene diversity was observed for primer mPgCIR256(0.6681) and lowest for primer mPgCIR24 (0.0377). SSR primer mPgCIR256 was most informative with high rateof polymorphism as well as number of alleles. Phenotypic correlation indicated the correlated traits with dependentyield trait. PCA and cluster analysis showed a significant phenotypic and genetic diversity among existing cultivars.All accessions were grouped into two major groups and under each group four sub groups. Maximum diversity wasfound in leaf traits, viz. leaf length, leaf breadth, petiole and petiole length. Genetic distance and the dissimilarity matrixshowed three major clusters on the basis of genetic similarity. All these accessions were grouped in to three clusters,viz. A, B and C. While cluster A includes only cultivars, cluster B includes all species except P. friedrichsthalianum.This indicates that, the diversity among and between species is at cluster level. Genetic diversity analysis amongPsidium species showed that P. guajava had more similarity with Psidium guienensis compared to other species.Present investigation indicated the presence of substantial diversity among guava species which can be utilized forfuture guava improvement programmes